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Icelandic Pseudocraters as Analogs to some Volcanic Cones on MarsPseudocraters are rootless vents formed by the interaction of lava flows with surface or near-surface water. This interaction can produce mild explosions and the accumulation of scoria and spatter into small constructs. Pseudocraters in several localities in Iceland were examined in the field and compared to similar appearing features observed on Mars. The Icelandic pseudocrater cones in this study range in size from 6 to 70 m in diameter, have summit craters which range from 2 to 28 m in diameter (many cones lack craters entirely), and have flanks that am either concave- up or convex-up. The size and spacing of Icelandic pseudo-craters might be a function of the availability of water, in which larger, closely spaced features result from efficient lava-water interaction, as suggested by the environments in which the features formed. Possible Martian pseudocrater cones in Amamnis Planitia range in diameter from 30 to 180 m and have craters 12 to 80 m in diameter. A numerical model for volcanic explosions was adapted to study the formation of pseudocraters under terrestrial and Martian conditions. The results suggest that explosions forming Martian cones require significantly less water (calculated masses am less by a factor of 4 to 16) than those forming Icelandic pseudokers, despite their larger sizes, This is attributed to the low gravity and atmospheric pressure in the Mars environment and is consistent with the likely lower abundance of water, which might be present as interstitial ice at shallow depths in the regolith. Locations of potential pseudocraters on Mars at latitudes as low as approximately 8 degrees N, imply the presence of crustal ice stores at the time of their formation.
Document ID
20030071709
Document Type
Reprint (Version printed in journal)
Authors
Greeley, Ronald (Arizona State Univ. Tempe, AZ, United States)
Fagents, Sarah A. (Arizona State Univ. Tempe, AZ, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Journal of Geophysical Research
Volume: o 106
Issue: E9
ISSN: 0148-0227
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
Paper-2000JE001378
Funding Number(s)
CONTRACT_GRANT: NAG5-11787
Distribution Limits
Public
Copyright
Other